X-ray apparatus



F. 5. SMITH X-RAY APPARATUS Feb. 7, 1933.

Filed March a, 1927 TWMJM IN V ENTOR ATTORNEY Patented Feb. 7, 1933 PATENT OFFICE FRANKLIN S. SMITH, OF BROOKLYN, NEW YORK X-RAY APPARATUS Application, filed March 3,

This invention relates to the cooling and insulating of electrodes that are maintained at relatively high potential, and more particularly to the cooling of the anode of an X- 5 ray tube and t0 the insulation from the relatively high potential of the anode of the various apparatuses associated with the latter.

Qneof the objects of this invention is to provide a simple and practical X-ray apparatus in which the cooling of the anode may be effected in a highly efiicient manner and with apparatus capable of inexpensive but durable construction and capable of great reliability of action. Another object is to provide an apparatus of the above-mentioned nature in which greater safety of operation of the high voltage apparatus is achieved than has heretofore been possible and in which the difiiculties of insulation or protection of the various parts of the apparatus from the high potentials employed are greatly minimized. Another object is to provide an apparatus in which high efficiency of insulation or isolation of the high voltage member to be cooled, from the various parts of the apparatus, may be achieved at minimum cost, and with minimum complication ofparts or structure. Another object is to achieve, in apparatus of the above-mentioned nature, a substantial avoidance of the difliculties of lubrication of such moving parts as are contained, for example, in the circulating pump for the cooling liquid, and thus to achieve great dependability and continuity of operation. Another object is to provide an X-ray apparatus of the abovementioned character well adapted to meet varying conditions of hard practical use. Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combination of elements, and arrangements of parts as will be exemplified in the structure to be hereinafter described and the scope of the application of p which will be indicated in the following 0 tures embodying my invention, certain parts 192?. Serial No. 172,281.

being shown in section in order to show the construction more clearly. i

As conducive to a clearer understanding of certain features of my invention, it might i be pointed outthat, in X-ray apparatus, for example, where very high potentials are employed, one of the greatest difficulties resides in cooling the anode of the X-ray tube and in effectively insulating the various parts that are subjected to the high potential. In the use of X-ray tubes, particularly for the sterilization of tobacco products, food products, and the like, it is not infrequent that potentials across theelectrodes of the X-ray tube as high. as 250,000 volts or more are em ployed during the substantially continuous operation of the apparatus. Various expedients have been devised and employed in the endeavor to minimize the difficulties attendant upon the cooling and insulation of the anode of the X-ray tube but such expedients have in general been cumbersome, complicated, and expensive, and have also been of such a character that a much desired safety, in behalf of the operatives who take care of the maintenance and operation of the apparatus, could not be efiectively achieved. Accordingly, it is one of the dominant aims of this inventionto achieve-a great simplifithe type adapted to have passed into thermal contact therewith a suitable cooling fluid, and accordingly the anode 12 is provided with a tubular conduit, of a generally spiral form, indicated at 14 and intimately associated with the anode 12. The tubular conduit 14 is of any appropriate metal and is pro vided with an inlet tube or connection 15 and an outlet tube or connection 16.

Any suitable electrical apparatus may be associated with the X-ray tube 10 for energizing the latter and as illustrative of a possible form of such apparatus, I have shown two serially connected condensers 17 and 18 connected across the anode 12 and the cathode 11 by conductors 19 and 20 respectively. The connection to the anode 12 may be made directly to one of the tubular connections, such as the member 16, while the connection to the cathode 11 may be made to the midpoint of the low voltage winding of the transformer 13, as shown in the drawing.

Any suitable means may be employed to charge the condensers 17 and 18 and as i1lustrative of a possible form of such apparatus, I have shown a transformer 21 having its high tension winding 22 connected intermediate of the condensers 17 and 18, as at 23, and grounded as at 24. The low voltage winding 25 of the transformer 21 may be connected as by conductors 26 and 27 to any suitable source of alternating current and is commonly connected to a suitable supply circuit, indicated at 28 and 29, of relatively low voltage.

The developed terminal of the high voltage winding 22 of the transformer 21 is connected to the movable member 30 of a synchronous switch adapted to be synchronously driven by any appropriate apparatus (not shown). The switch member 30 operates between two fixed contacts 31 and 32, spaced apart by an electrical angle, so that, at one half wave of the alternating potential of the high tension winding 22, the charging circuit to the condenser 17 is closed (with the parts in the position shown in the drawing) but through any suitable rectifying valve 33, interposed in the conductor 34 leading from the switch contact 31 to the other terminal of the condenser 17 while, at the next half wave, the charging circuit of the other condenser 18 is closed through the switch member 30, fixed switch contact 32, conductor 35 and a suitable rectifying valve 36 interposed in the latter conductor leading to the other terminal of the condenser 18. The rectifying valves insure that any one condenser, upon being charged, doe'snotback discharge through its charging circuit.

Among the advantages of an electrical energizing circuit such as that described above, may be noted the fact that each condenser may be charged at a voltage substantially about one-half of the voltage across the electrodes of the X-ray tube 10 so that if, for example, the X-ray tube 10 is intended to operate at a voltage of about 250,000 volts, each condenser need be charged to only a voltage of about, or sli 'htly in excess of, 125,000 volts while the big tension winding 22 of the transformer 21 need likewise be of only that of the charging voltage of the individual condensers, hence in the neighborhood of about 125,000 volts. Furthermore, the arrangement such as that described above, in being grounded at 24, brings about such a distribution of potentials in the electrical system that, even though the voltage difference between the electrodes of the X-ray tube 10 be as high as 250,000 volts, yet the relative potential difference between any one electrode of the X- ray tube 10 and ground is only 125,000 volts. Even the employment of such an expedient, however, makes necessary the insulation of various other parts of the apparatus for a voltage on the order of 125,000 and still entails many disadvantages and defects in this latter connection. Even with such an arrangment, however, associated mechanical apparatus and associated electrical apparatus, even if of relatively low voltage, have to be constructed and arranged to be insulated against a relatively high voltage. Such disadvantages are effectively overcome by reason of certain features of my invention.

At 37 I have indicated a pump preferably of the sump type and appropriately suspended within a container 38. Conveniently, the pump is suspended from the upper closing member 39 of the container 38, the container being thereby preferably sealed. Supported above the container 38 and by appropriate brackets 40 is an electric motor 41, its shaft 42 extending vertically and downwardly through the. closing member 39 of the container 38 and connected in any suitable; manner with the shaft 43 of the pump 37. The pump 37 may be of the rotary vane type and its shaft may be and preferably is supported in bearings 43 and 44, the arrangement being such that the several movable parts of the l pump are substantially exposed to the fluid which the pump handles. Any suitable stufling box 66, preferably having a bearing 67 for the passage of the shaft 43 to the upper closing member 39 of the casing 38'may be employed.

Connected to the outlet tube 16 is a conduit generally indicated at 45; this conduit 45 is made of solid dielectric material, such as bakelite, for example, and is of sufficient length in an axial direction to amply with stand the potential to which the anode 12 is subjected, so that the high potential tubular connection 16 is thus effectively insulated from the metallic tubular conduit 46 which is connected to the lower end of the solid dielectric conduit 45 and leads, as indicated, into the receptacle 38. The cooling medium, preferably a liquid, may collect in the container 38, so that, upon subsequent operation of the pump 37, the intake 47 of the pump may be well supplied with the cooling liqu1 The outlet 48 of the pump 37 is connected by the metallic tubular conduit 49 to an appropriate heat-exchange device generally indicated at 50. Conveniently, this heatexchange device 50 may comprise a series of tubes 51 in connection with the outlet conduit 49 from the pump and a suitable housing 52 aboutrthe tubular conduits and open at the bottom; the housin 52 is connected at its upper end to the intake 53 of a suitable suction deviceor blower 54, driven by a motor 55, and adapted to draw air rupwardly through the housing 52, extract heat from the cooling ;liquid in 'the conduits 51, and discharge the heatedair through the'discharge conduit 56. i The'outlet end of the conduits 51 is connected by the tube orpipe 57 to the inlet tube or connection 15 of the anode 12 of the X-ray tube 10, but through a tubular conduit member 58 of soliddielectric material. Conveniently, the tubular conduit 58 is of dimensions substantially identical to those of the-conduit 45, heretofore described, and hence is adapted to insulate thehigh potential inlet connection 15 from the metallic pipe orcon.- duit 57 and the apparatus connected with the latter. The conduit 57 is grounded as at 59 w and thus the heat-exchange device 50 with its ble qualities of the oil.

associated apparatus'and the pump 37 with f its associated apparatusare maintained at substantially ground potential.

In the circulating system thus formed, there is preferably employed as a cooling medium a non-inflammable dielectric liquid; this liquid may conveniently consist of a mixture of oil, such as is used in insulating electrical apparatus, and a suitable ingredient for rendering the oil non-inflammable,

such as carbon tetrachloride, the latter .in'

sufiicient quantity to negative thecombusti- The ingredient added to the oil, moreover, is also an insulating dielectric medium. The resultant mixture is thus both ofhigh dielectric strength and non-inflammable.

. The direction in which thedielectric cool-' ing and insulating fluid is passed through the circulating system will be clear from the foregoing description and is, furthermore,

indicated by the various arrows on the drawing. In passing through the pump 37, the latter being submerged below the level of the liquid collected in the container 38, the relatively movable parts of the pump, either the shaft and its hearings or the rotating vanes,

if the pump is of the rotary vane type, are

thus effectively lubricated While at the same time, in being circulated through the circulating system, and particularly in passing through the dielectric conduits and 58, the

high potential anode 12 and its connecting conduits 15 and 16 have the very'high potential at which they are maintained efli'ectively isolated from allof the apparatus which is connected thereto through the insulating tubes 45 and 58, such apparatus being preferably, as hereinbefore noted, maintained at substantially ground potential b the grounded connection at 59. It will un- ,derstood that the dimensions of the insulat- "ing conduits 45 and 58 may be and preferably are selected with due regard to the dielectric properties of the dielectric cooling fluid and to the dielectric properties ofthe solid insulatingmaterial itself of which the tubes 45 and 58, are made.

The pump and heat-exchange device, together with'their associated apparatuses and drivingcmotors, are thus effectively insulated against the high potential at which the anode 12 is operated. Thus, the motor 41 driving the pump 37 may be directly connected as by the conductors 59 and 60 to the relatively low tension supply circuit 2829, while the motor 55 driving the fan or blower54 may a A similarly be connected as by conductors 61 and 62 to the low tension supply circuit 2829, all without necessitating either the insulation of the electrical circuit of the motor from the mechanical portions thereof to withstand the high potential of the anode 12 z and without necessitating the interpositioning, as is the usual practice, of a transformer between the motor or motors and the low tenr sion supply circuit and with the transformer constructed to withstand the high potential of the anode. Furthermore, the heat-exchange device and the pump 37 with its container 38 need not be insulatingly supported on insulating pedestals, as is the usual practice, to withstand the high potential of the X-ray apparatus but, moreover, in being effectively insulated from the high potential anode and dependably maintained at ground potential by the ground connection '59 are in a condition such that they'may be given ing fluid being circulated in the cooling system. These instruments, it will be noted, are also Well safeguarded against the high potential in the X-ray tube and may thus be consulted without danger from any of the high potentials in"the apparatus.

It will thus be seen that there has been provided in this invention an X-ray system and apparatus in which the cooling of the anode may be dependably and reliably achieved with apparatus which is at once Y2 simple, of inexpensive construction, highly reliable operation, and characterized by great safety of operation. Furthermore, it will be seen that the various pipes or conduits associated with the heat-exchange device and the pump may be made of metal throughout, thereby insuring the achievement of corresponding advantages that flow from the use of a hydraulic system or circuit made of metallic conduits, but all without detracting from the many electrical advantages which the invention achieves. It will furthermore be seen that the apparatus provided in this invention is of a thoroughly practical nature and well adapted to meet the varying conditions of hard practical use.

As many possible embodiments may be made of the above invention and as many changes might be made in the embodiment above set forth, it is to be understood that all matter hereinbefore set forth or shown in the accompanying drawing, is to be interpreted as illustrative and not in a limiting sense.

I claim as my invention:

1. In X-ray apparatus, in combination, an X-ray tube having an anode and a cathode; means forming a supply of alternating current of relatively low potential means including a step-up transformer connected between said supply and the electrodes of said tube for energizing the latter at relatively high potential; a circulating system for passing a cooling fluid in thermal contact with said anode, said system including a' heat exchange device, a pump, and conduit means, the latter having a portion thereof made of solid dielectric material and interposed between said anode and the rest of the circulating system; a fluid dielectric in said system for circulation therethrough by said pump; and electromotive means for operating said pump and said heat exchange device and supplied with energy from said low potential supply, the electrical circuit of said electromotive means being insulated for a relatively low potential on the order of that of said supply.

2. In X-ray apparatus, in combination, an X-ray tube having an anode and a cathode; means forming a supply of alternating current of relatively low potential; means including a step-up transformer connected be tween said supply and the electrodes of said tube for energizing the latter at relatively high potential; a circulating system for passing a cooling fluid in thermal contact with said anode, said system including a heat exchange device, a pump, and conduit means, the latter having a portion thereof made of solid dielectric material and interposed between said anode and the rest of the circulating system; a fluid dielectric in said system for circulation therethrough by said pump; and an electric motor for driving said pump, said motor being supplied with energy from said supply and the electrical portions thereof being insulated for a voltage on the order of that of said supply.

3. In X-ray apparatus, in combination, an

i X-ray tube having an anode adapted to be maintained at relatively high potential, said anode having associated therewith a passage having an inlet and an outlet for conducting a cooling fluid into thermal contact with said anode; a heat transferring device; a pump; conduit means for connecting said inlet and outlet to said heat transferring device and pump, thereby to form a circulating system for a cooling fluid; and a liquid dielectric in said circulating system, said connecting conduit means having the portion thereof which is connected to said inlet and outlet made of dielectric material.

4. In X-ray apparatus, in combination, an X-ray tube having an anode and a cathode, said anode being maintained at relatively high potential during normal operation of said tube and having metallic tubular connections; a circulating system for passing a cooling fluid into thermal contact with said anode, said system including an interconnected heat exchange device and pump, said device and pump being maintained at substantially ground potential relative to the high potential of said anode, and conduit means made of solid dielectric material interposed between the high potential anode connections and the low potential parts of the circulating system; and a fluid dielectric in said system for circulation by said pump.

5. In X-ray apparatus, in combination, an X-ray tube having an anode and a cathode, said anode being maintained at relatively high potential during normal operation of said tube and having metallic tubular connections; a circulating system for passing a cooling fluid into thermal contact with said anode, said system including an interconnected heat exchange device and pump having a bearing constructed to be substantially exposed to the fluid handled by the pump, said device and pump beingmainta-ined at substantially ground potential relative to the high potential of said anode, conduit means made of solid dielectric material interposed between the high potential anode connections and the low potential parts of the circulating system; and a cooling fluid comprising a liquid dielectric having lubricating properties in said system for circulation by and through said pump.

6. In X-ray apparatus, in combination, an X-ray tube having an anode and a cathode, said anode being maintained at relatively high potential during normal operation of said tube and having metallic tubular connections; a circulating system for passing a cooling fluid into thermal contact with said anode, said system including an interconnected heat exchange device and pump, said device and pump being maintained at substantially ground potential relative to the high potential of said anode, and conduit means made of solid dielectric material interposed combination, a pump maintained at substantially ground potential; an electrode adapted to be maintained at relatively high potential; conduit means connecting said pump and said electrode for the passage of a cooling fluid into thermal contact with said electrode, said conduit means having a portion thereof which is interposed between said electrode and said pump made of non-conducting material to insulate the high potential electrode from the low potential pump; a fluid dielectric in said systemfor circulation by said pump; and means for cooling said fluid dielectric.

8. In a system for cooling electrodes, in

combination, a pump maintained at substan tially ground potential and having relatively movable parts thereof substantially exposed to the fluid handled thereby; an electrode adapted to be maintained at relatively high potential; conduit means connecting said pump and said electrode for the passage of a cooling fluid into thermal contact with said electrode, said conduit means having a portion thereof which is interposed between said electrode and said pump made of non-conducting material to insulate the high potential electrode from the low potential pump ;a liquid dielectric having lubricating properties in said system for circulation by and through said pump; and means for cooling said liquid dielectric.

9. A heat-exchange device adapted to extract heat from a fluid passed therethrough and maintained substantially at ground potential; an electrode adapted to be maintained at relatively high potential; conduit means connecting said heat exchange device and said electrode for the passage of a cooling fluid into thermal contact with said electrode, said conduit means being constructed so that a portion thereof intermediate of said highpotential electrode and said low potential heat exchange deviceis non-conducting and insulates the former from the latter; and a fluid. dielectric for passage through said conduit means and said heat exchange device.

10. In a system for cooling electrodes, in combination, a pump maintained at substantially ground potential: an electrode having an inlet conduit and an outlet conduit maintained at relatively high potential: means connecting said pump and said inlet and outlet conduits to form a circulating system for a cooling fluid, said means including two conduit sections of solid dielectric material respectively connected to said inlet and outlet conduits; a fluid dielectric in said system; and means for cooling said dielectric.

11. In .a system for cooling an electrode, in combination, an'electrode adapted to be maintained at relatively high potential;

means forming a supply of alternating current of relatively low potential; means including a step-up transformer connected between said supply and said electrode for maintaining the latter at relatively high potential; a circulating system for passing a cooling fluid'into thermal contactwith said electrode, said system including a heat: exchange device, a pump, and conduit means, the latter havingrportions thereof made of solid dielectric material and interposed between said electrode and the rest of the circulating system; a fluid dielectric in said system for circulation therethrough by said pump; and an electric motor for driving said pump, said motor I being supplied with energy from said supply and the electrical portions thereof being insulated for a voltage on the order of that of said supply.

12. In a system for cooling an electrode, in combination, an electrode adapted to be maintained at relatively high potential; means forming a supply of alternating current of relatively low potential; means including a step-up transformer connected between said supply and said electrode for maintaining the latter at relatively high potential; a circulating system for passing a cooling fluid into thermal contact with said electrode, said system including a heat exchange device, the latter including means driven by an electric motor for passing a cooling fluid into thermal contact therewith, and conduit means, the latter having portions thereof made of solid dielectric material and interposed between said electrode and said heat exchange device; and a fluid dielectric in said system for circulation into thermal contact with said electrode and through said heat exchange device, said motor being supplied with energy fromsaid supply and the electrical portions thereof being insulated for a voltage on the order of that of said supply.

13. In a system for cooling electrodes, in a for passage through said conduit means and said electrode passage.

14. In a system for cooling electrodes, in

combination, an electrode adapted to be maintained at relatively high potential; means for guiding a cooling fluid into thermal contact with said electrode, said means including a conduit section of solid dielectricmaterial; means for effecting movement of a cooling fluid through said guiding means and connected to the latter so that said conduit section of solid dielectric material is interposed therebetween and said electrode; and a fluid dielectric for passage through said guiding means. i

15. In a system for cooling an electrode, in combination, a electrode adapted to be maintained at relatively high potential, means in cluding a pump for passing a cooling liquid into thermal contact With said electrode, and

' a lubricating non-inflammable and dielectric liquid therefor comprising a mixture of oil and a liquid dielectric having also the property of negativing the combustibility of the oil, the oil component acting also to lubricate said pump.

In testimony whereof, I have signed my name to this specification this 23rd day of February, 1927.

' FRANKLIN S. SMITH. 

